Gradient-channel quaternized chitosan/corncob-based aerogel membranes for efficient oil-water separation and dye removal.

Oil-containing wastewater, particularly surfactant-stabilized oil-in-water emulsions, remains extremely challenging to treat due to its high stability and complex composition. In this study, a gradient porous aerogel membrane was prepared using quaternized chitosan and corn cobs via directed freezing and freeze-drying techniques. Quaternized chitosan endows the membrane with inherent hydrophilicity and a positively charged surface, while the incorporation of corn cobs enhances mechanical strength and improves dye removal capacity. The gradient pore structure further generates a capillary-assisted transport effect, thereby enhancing separation performance. This combination of structure and function confers the membrane with underwater superoleophobicity and electrostatic interaction capabilities, enabling efficient oil-water separation and dye adsorption. The membrane exhibited the most outstanding separation performance in both immiscible oil-in-water mixtures (11,190 L m-2 h-1, 99%) and oil-in-water emulsions prepared with anionic surfactants (1200 L m-2 h-1, 97%), while effectively removing various dyes and demonstrating good cycling stability. This study proposes a bio-based strategy that integrates structural regulation with interfacial functionality, providing a highly promising platform for multifunctional wastewater treatment.